A father-in-law purchased a house for his son and daughter-in-law to live in. The house was put in the father's name alone. He paid the deposit as a wedding gift and promised the couple that if they paid the mortgage instalments, the father would transfer the house to them. The father then became ill and died. The mother inherited the house. After the father's death the son went to live with his mother but the wife refused to live with the mother and continued to pay the mortgage instalments. The mother brought an action to remove the wife from the house.

Held:

The wife was entitled to remain in the house. The father had made the couple a unilateral offer. The wife was in course of performing the acceptance of the offer by continuing to meet the mortgage payments. Under normal contract principles an offer may be revoked at any time before acceptance takes place, however, with unilateral contracts acceptance takes place only on full performance. Lord Denning held that once performance had commenced the Mother was estopped from revoking the offer since it would be unconscionable for her to do so. Furthermore there was an intention to create legal relations despite it being a family agreement.